静电自由电子激光摆动器

静电自由电子激光使用静电摆动场代替静磁摆动场产生相干受激辐射。本文提出了一种静电自由电子激光摆动器。这种摆动器可以产生周期从3cm到5mm,辐值比较大的圆极化摆动场,有利于自由电子激光的进一步研究。     

新型Wiggler自由电子激光中的Madey定理

用单粒子方法推导出了Ｓｈｌｏｍｏ Ｐｉｎｈａｓ提出的一种新型摆动器－磁场与Ｚ轴无关的摆动器自由电子激光中的Ｍａｄｅｙ定理。结果表明：在这种摆动器自由电子激光中，Ｍａｄｅｙ定理第一部分形式不变；第二部分相差一个因子Ｍ０，它说明新型摆动器自由电子激光比普通摆动器自由电子激光有更高的能量转换效率。     

面电流摆动器与线电流摆动器自由电子激光理论

从电子轨迹的相似性出发，用类比的方法得到了面电流摆动器和线电流摆动器自由电子激光的自发辐射谱；然后用单粒子理论推导出了自发辐射与受激光辐射的关系，根据这种关系求出了两种电流摆动器自由电子激光的小信号增益。     

等离子体波摆动器中电子运动的混沌特性

本文用Ｐｏｉｎｃａｒｅ截面及Ｌｙａｐｕｎｏｖ指数两种方法，研究了新型的等离子体波摆动器中电子运动的混沌特性，结果表明，当摆动器强度增大时电子从规则运动向混沌状态发展，这是提高自由电子激光输出功率时必须解决的一个重大课题。     

有轴向磁场的平面摆动器自由电子激光

研究了电子在有同向磁场的平面摆动器中的自发辐射和谐波相干辐射，得到了一个较普遍的自发辐射谱表达式和谐波自由电子激光的增益。当电子的能量较高或者沿摆动器轴线观察时，辐射是椭圆极化的，适当附加轴向磁场，可以提高激光增益，对于较低次谐波，增益提高更明显。     

新型摆动器自由电子的自发辐射

Ｓ．Ｐｉｎｈａｓ于１９９０年提出一种新型摆动器－－磁场与纵向坐标无关摆动器。本文在Ｓ．Ｐｉｎｈａｓ工作的基础上，利用广义Ｂｅｓｓｅｌ函数计算了电子在这种摆动器中运动产生的自发辐射强度分布，得到了一筱较普遍的自发辐射谱表达式。结果表明：新型摆动顺自由电子的自发辐射谱与普通平面摆动器自由电子的自发辐射谱相似，谱线 形状由ｓｉｎｃ（η）函数决定。     

周期弯曲晶体的摆动场辐射作为短波长激光的可能性

指出了用传统方法把自由电子激光(FEL)推向更短波长将在技术上遇到严重挑战,并试图寻找新的光源.在周期弯曲晶体中作沟道运动的粒子,在沟道辐射的同时,还将不断产生摆动场辐射.在摆动场轨道曲率最大或最小处,摆动场辐射与粒子束平行,情况与自由电子激光类似.在摆动场轨道曲率相继最大(或最小)处产生的光子是受激的,且频率比常规自由电子激光高得多.在简谐近似下,描述了沟道辐射和摆动场辐射频率与频谱分布,讨论了沟道辐射和摆动场辐射之间的关系,分析了利用晶体摆动场辐射作为X-激光或γ-激光的可能性.     

磁场与z轴无关摆动器自由电子激光的自发辐射与受激辐射

本文讨论了磁场与z轴无关摆动器自由电子激光中的能量损失和能量离散以及它们相应的意义.分析、计算了自发辐射和受激辐射.结果说明:自发辐射正比于电子能量离散;光功率增益正比于平均电子能量损失.     

以长直载流导线磁场作摆动器场的自由电子激光的Madey定理

Ｓ．Ｐｉｎｈａｓ提出以长直载流导线磁场作为摆动器场产生自由电子激光的新思想。本文利用单粒子理论推导出了反映自发辐射与受激辐相关第的Ｍａｄｅｙ定理在这种磁场中的对应形式。结果表明：Ｍａｄｅｙ定理的第一部分形式不变；而第二部分有相似形式，但相关一个倍乘因子。     

二维摆动磁场自由电子激光自发辐射的频谱特性

本文对二维摆动磁场自由电子激光的自发辐射频谱进行了理论分析，并对分析结果进行了数值计算。计算结果表明，采用ｌ（ｌｋ２＝ｋｙ）值不同的二维摆动磁场，可以增强第ｌ次谐波的自发辐射强度，从而能够有选择地实现自由电子激光的高次谐波运转。     

电子在磁场与纵向坐标无关的摆动器中的辐射谱分布

应用Ｍａｄｅｙ定理计算了电子在ＳｈｏｌｍｏＰｉｎｈａｓ提出的一种磁场与纵向坐标无关的摆动器中自发辐射谱分布，并将所得到的结果与利用线性摆动器时产生的辐射谱进行了比较，发现它们有相同的形式。初步论证了利用该摆动器产生高次谐波相干辐射的可能性。     

等离子体尾波场摇摆器自由电子激光

自由电子激光的小型化和实现激光短波长一直是自由电子激光领域的研究热点,而短周期、强场摇摆器是解决此问题的行之有效的途径。文章分析了利用等离子体尾波场作为自由电子激光摇摆器的机制,推得自由电子的自发辐射谱,利用麦迪定在线阵列理论求得电子的受激辐射公式,得到小信号增益。     

Three dimensional gain analysis of free electron laser with focusing permanent magnet wiggler

A three dimensional simulation software system developed to estimate a free electron laser (FEL) gain has been applied to FEL using a standard plane polarized wiggler and an alternately shifted magnet wiggler. It is seen for the latter wiggler that a large filling factor could be selected and each maximum gain corresponding to each orbit of electron beam concentrates at a certain frequency region of FEL radiation. It is, therefore, implied that a proper shift between the adjacent magnets in the wiggler produces the improvement of the FEL gain.     

一种由强光担任摇摆器的新型自由电子激光器及其增益分析

提出了一种由超短脉冲双光束担任摇摆器的自由电子激光器的原理及设计方案,并在单电子近似的基础上给出了计算其增益的联立方程组,以用于数值模拟.指出了实现一种紧凑、廉价的可调谐光源的可能性.     

A solenoid-derived wiggler

A novel wiggler design for use in free-electron lasers (FELs) is proposed, consisting of a staggered array of magnetic poles situated inside the bore of a solenoid. The resultant field pattern consists of a periodic transverse magnetic field on axis, as well as a longitudinal guide field. Such a wiggler has several advantages: the longitudinal field acts to confine the electrons near the FEL axis, high fields can be attained at short wiggler periods, the field strength is easily varied, and fabrication and testing of the wiggler are relatively easy. It is planned to use this wiggler design in a far infrared FEL to be built at Stanford University     

渐变Wiggler技术在低能电子束喇曼型自由电子激光器中的应用

本文利用有质动力势导出了自由电子激光器效率提取表达式,分析了渐变Wlggler技术对提高激光器效率的作用,并利用这一技术进行了渐变Wiggler场强自由电子激光器实验。结果表明其效率是相应恒定Wiggler自由电子激光器的2.6倍。     

Novel approaches to FEL operation: The gas-loaded FEL and a high efficiency FEL design

Two novel methods for improving free-electron laser (FEL) oscillator performance are discussed: (a) The gas-loaded FEL (GFEL) allows operation at snorter wavelengths for a given accelerator energy and wiggler. Experimental results of laser operation with a gas retention foil in the electron beam line and with the introduction of gas to the wiggler cavity are presented, (b) An FEL design utilizing a time-ramped microwave field to accelerate electrons as they lose energy to radiation allows for high conversion efficiencies. Parameter constraints for such an FEL are discussed, leading to a structure that integrates a wiggler with a linac. It is shown that conversion efficiencies of 50% at λ = 10 μm with a 2m wiggler length can be achieved for typical FEL parameter values without sacrificing small-signal gain     

A staggered-array wiggler for far-infrared, free-electron laseroperation

A staggered-array wiggler for a far-infrared free-electron laser (FEL) has been built at Stanford, and its magnetic properties have been tested. This type of wiggler has several desirable features: high wiggler field at short wiggler periods, wavelength tuning by a solenoid current, electron beam confinement by a solenoid field, and looser machining tolerances. A 10.8-kilogauss peak wiggler field has been measured at a 7.0-kilogauss solenoid field for a 1.0-cm wiggler period and a 2.0-mm gap. The small-signal gain has been calculated analytically and by computer simulation for a 0.5-m long wiggler. For an 8-A, 9-ps current pulse and a 3.3-MeV electron beam, 5-dB gain is predicted. Twenty- to thirty-percent wavelength tuning can be achieved by adjusting the solenoid field and still maintain reasonable small-signal gain. The pulsed-wire technique was employed to test the field uniformity of this novel wiggler, and the measured field variation was about 1%     

FEL gain reduction due to wiggler errors

We report the results of a study comparing an analytical theory of wiggler errors in free-electron lasers (FEL's) to a numerical simulation. The different mechanisms of reduction in FEL gain due to wiggler errors are reviewed, and in each case analytical results are compared with computer simulation and shown to be in good agreement. We present a study of the proposed UV FEL user facility at BNL and determine the implications of the wiggler errors on the FEL design     

The effect of wiggler imperfections on nonlinear harmonicgeneration in free-electron lasers

The generation of harmonics through a nonlinear mechanism driven by bunching at the fundamental has sparked interest in using this process as a path toward an X-ray free-electron laser (FEL). An important issue in this regard is the sensitivity of the nonlinear harmonic generation to wiggler imperfections. Typically, linear instabilities in FELs are characterized by increasing sensitivity to both electron beam and wiggler quality with increasing harmonic number. However, since the nonlinear harmonic generation mechanism is driven by the growth of the fundamental, the sensitivity of the nonlinear harmonic mechanism is not severely greater than that of the fundamental. In this paper, we study the effects of wiggler imperfections on the nonlinear harmonics in a 1.5-Å FEL, and show that the decline in the third harmonic emission with increasing levels of wiggler imperfections roughly tracks that of the fundamental